Agrobacterium tumefaciens biovar 3, the causal agent of crown gall of grapevine (Vitis spp.) (Burr, T.J., and Katz, B.H. 1984. Grapevine cuttings as potential sites of survival and means of dissemination of Agrobacterium tumefaciens. Plant Dis. 68:976-978; Kerr, A. and Panagopoulos, C.G. 1977. Biotypes of Agrobacterium radiobacter var. tumefaciens and their biological control. Phytopathol. Z. 90:172-179; Panagopoulos, C.G., and Psallidas. P.G. 1973. Characteristics of Greek isolates of Agrobacterium tumefaciens (E.F. Smith & Townsend) Conn. J. Appl. Bacteriol. 36:233-240; and Sule, S., 1978. Biotypes of Agrobacterium tumefaciens in Hungary. J. Appl. Bacteriol. 44:207-213) survives benignly in grapevine xylem, and is transmitted by vegetative propagation (Burr. T.J., and Katz. B.H. 1984. Grapevine cuttings as potential sites of survival and means of dissemination of Agrobacterium tumefaciens. Plant Dis. 68:976-978 and Lehoczky. J. 1968. Spread of Agrobacterium tumefaciens in the vessels of the grapevine after natural infection. Phytopathol. Z. 63:239-246). Tumor production follows wounding of systemically infested vines by winter injury or mechanical means (Dhanvantari, B.N. 1983. Etiology of grape crown gall in Ontario. Can. J. Bot. 61:2641-2646; Lehoczky. J. 1968. Spread of Agrobacterium tumefaciens in the vessels of the grapevine after natural infection. Phytopathol. Z. 63:239-246; and Lehoczky. J. 1978. Root system of the grapevine as a reservoir of Agrobacterium tumefaciens cells. Proc. 4th Int. Conf. Plant Path. Bact. (Angers, France) 1:239-243). Possible strategies for controlling spread of the pathogen include indexing and certification of propagation wood (Tarbah. F.A., and Goodman. R.N. 1986. Rapid detection of Agrobacterium tumefaciens in grapevine propagating material and the basis for an efficient indexing system. Plant Dis. 70:566-568). Several methods for testing propagation stocks have been proposed, one relies on colony appearance on selective media (Tarbah, F.A., and Goodman, R.N. 1986. Rapid detection of Agrobacterium tumefaciens in grapevine propagating material and the basis for an efficient indexing system. Plant Dis. 70:566-568). However, endophytic bacteria similar in appearance to Agrobacterium tumefaciens biovar 3 on selective medium are present in grape xylem and this can lead to unnecessary rejection of plant material in an indexing scheme depending exclusively on colony appearance for diagnosis. Subsequent testing of numerous strains to identify Agrobacterium tumefaciens biovar 3 is time consuming. and labor intensive (Miller, H.J., and Vruggink, H. 1981. An assessment of biochemical and serological tests for Agrobacterium radiobacter subsp. tumefaciens. Phytopath. Z. 102:292-300 and Moore, L.W., Anderson, A., and Kado, C.I. 1980. Agrobacterium. In Laboratory Guide for Identification of Plant Pathogenic Bacteria, N.W. Schaad, ed., pp. 17-25. American Phytopathological Society, St. Paul). Serological assays provide more reliable diagnosis, but the presence of common epitopes in nontarget bacterial species can lead to false positive diagnoses due to cross reacting sera (Calzolari, C., Bazzi, C., and Mazzuchi, U. 1982. Cross-reactions between Corynebacterium sepedonicum and Arthrobacter polychromogenes in immunofluorescent staining. Potato Res. 25:239-246 and Crowley, C.F., and DeBoer, S.H. 1982. Nonpathogenic bacteria associated with potato stems cross-react with Corynebacterium sepedonicum in immunofluorescence. Am. Potato J. 59:1-7). Also, previous attempts to develop biovar-specific antisera have not been successful (Keane, P.J., Kerr, A., and New, P.B. 1970. Crown gall of stone fruit. II. Identification and nomenclature of Agrobacterium isolates. Aust. J. Biol. Sci. 23:585-595 and Miller, H.J., and Vruggink, H. 1981. An assessment of biochemical and serological tests for Agrobacterium radiobacter subsp. tumefaciens. Phytopath. Z. 102:292-300).
Hybridoma techniques, developed by Kohler and Milstein (Kohler, G., and Milstein, C. 1975. Continuous cultures of fused cells secreting antibodies of predefined specificity. Nature 256:495-497), allow production of antibodies specific to single epitopes, selected according to the investigators' design, thereby eliminating the problem of cross-reaction. Application of monoclonal antibodies to diagnosis or detection of several bacterial plant pathogens has been reported (Alvarez, A.M., Benedict, A.A., and Mizumoto, C.Y. 1985. Identification of Xanthomonas compestris pv. campestris with monoclonal antibodies. Phytopathology 75:722-728: De Boer and Wieczorek, A. 1984. Production of monoclonal antibodies to Corynebacterium sepedonicum. Phytopathology 74:1431-1434 and Halk, E.L., and De Boer, S.H. 1985. Monoclonal antibodies in plant disease research. Ann. Rev. Phytopathol. 23:321-350).
The production of a monoclonal antibody specific to Agrobacterium tumefaciens biovar 3 for application to detection and diagnosis of grape crown gall would be of great importance to the grape industry.